324 



STATE BOARD OF AGRICULTURE. 



mentj the fact that the fixation of ammonia correlates with the exchange of 

 calcium indicates that the same general causes are operating in each case 

 although perhaps to a different degree. The analytical determinations may- 

 have been influenced by ammonia from soil organic matter since the results 

 for fixed NH4 are lower than the potassium equivalents. More of the cations 

 of the salts was fixed by the alkaline soils of similar classes than the acid soils, 

 except, again, the acid clay loam which fixes more of the cations and liberates 

 more calcium than the alkaline clay loam. There was no evidence of fixation 

 of anions from these salts. 



TABLE 3. — Fixation of potassium fro?n KiSOt and KNO3 and ammonia from (,NHi)iSOi. 



Potassium added 0.391 gm. SO^ added 0.4S03 gm. 

 Potas.slum added 0,381 gm. NO' added 0.620 gm. 

 NH« added 0.1804 gm. SO< added 0.4803 gm. . 



Fixation of Calcium and Magnesium from Neutral Salts 



Since the foregoing data indicate that the fixation of potassium and 

 ammonia by the soils may be due chiefly to the quantity of calcium and 

 magnesium contained in them in condition to react, it was considered advisa- 

 ble to experiment with calcium and magnesium salts to determine their re- 

 lationships. Accordingly the soils were treated with solutions of Ca(N03)2, 

 CaS04, CaCl2 and MgCl2, the experimental procedure being the same as 

 that followed in previous cases. Tables 4 and 5 contain the results of this 

 experiment. 



